


just the two of us (we can make it if we try)

by IShipItAllAndThenSome



Category: Supergirl (TV 2015)
Genre: Alex Danvers Knows Kara Danvers Is Supergirl, Black Kryptonite Nonsense, Canon Compliant, F/F, Kryptonite - Freeform, Lena Luthor Knows Kara Danvers Is Supergirl, Lena is a Repressed Mess (canon), Not Canon Compliant, Possession, Post Episode: s4e12 Menagerie, Pseudoscientific Jargon, Rara - Freeform, but also sort of, literally the most self indulgent stupid shit
Language: English
Status: Completed
Published: 2019-03-09
Updated: 2019-03-09
Packaged: 2019-11-14 05:55:03
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 3,386
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18046778
Author URL: https://archiveofourown.org/users/IShipItAllAndThenSome/pseuds/IShipItAllAndThenSome
Summary: If Lena had known, all those months ago, the price of her choice to manufacture Harunel, the outcome of using it to splice Reign from Sam, the cost of Kara trying to kill her…She might have made very different choices.||AU of Supergirl Season 4 in which exposure to Harun-El (Black Kryptonite) while killing Reign created Rara as a sort of evil alter-ego inside Kara. Kara lost control of her and has now been taken over by Rara, who is in D.E.O. custody; Alex and Lena want to fix this, while President Baker wants to use her as a weapon. Unfortunately inspired by the Monster arc in Season 4 of SyFy's The Magicians.





	just the two of us (we can make it if we try)

**Author's Note:**

> i've had A Week (actually mostly just A Day but like it felt like a week) and then today i got caught up on the magicians and was like "what if i took [this scene](https://www.youtube.com/watch?v=kjcQlZ4r-Jc) and made it women"  
> and then it turned out to be international women's day so like...
> 
>  
> 
> [via GIPHY](https://giphy.com/gifs/goldenglobes-golden-globes-2018-l1IBjEJkRygVUM2cM)

Lena—alone, now, and aching for the one person who she truly loved— made the very stupid call of going to look at her. Just look, from a distance. Like Kara’s face, through the glass, with someone else’s mind behind her kind eyes, would be enough to soothe her, make her feel a little less unmoored.

She knew it was a mistake. From the moment the thought crossed her mind, she knew, and she did it anyway.

How could she ever resist?

“I know you’re watching me,” she said silently, mouth moving on the security monitor with no sound coming through. “I can hear your little heart, Lena. Come take a look in person.”

Again, a terrible idea. Again, irresistible.

She went. Her intentions, ever good, were to go no further than the doorway into the hall lined with cells. To stand, twenty feet away, take one look, and leave.

And so she did. She stood in the doorway, practically hugging herself, fingers digging into the meat of her upper arms as she crossed them against her ribs, shoulder pressing into raw concrete as if to anchor herself there.

And so she saw, as always, Kara: soft curls and rosy cheeks and expressive mouth, her eyes shining under the fluorescent lights, her square shoulders and deliberate posture, limbs akimbo and hands on hips. The scar on her forehead and the way her cheeks rounded out when she smiled. She could almost smell the ozone that clung to her like perfume from so many lower atmosphere patrols.

“Hello, Lena,” said the creature, in a voice which was Kara’s pitch and resonance and the inflection of someone, something, else entirely.

Still, it was her voice. Her mouth, moving.

Lena took a step forward in spite of herself, helpless, stumbling.

“Why don’t you let me out?”

Another step. Unintentional, of course. The toe of her boot caught on the floor and barely stopped a third step from happening.

“We could have fun, Lena, just the two of us.” Those blue eyes sparkled; that warm smile widened, revealing charming dimples, baring perfect teeth.

Maybe so.

“Tell me about flowers, Lena. Quantum entanglement. Genetic engineering. Nuclear fission.” She pouted, a charming expression that felt very Kara, very authentic.

Muscle memory; Lena needed so badly to believe it was muscle memory, not something imitated by this monster, but something innate to Kara, still alive in there, part of her peeking through.

“I’m so bored!” she drawled, spreading her arms, splaying her fingers, tossing her head.

“I’m sure it’s very boring, being trapped here,” Lena found herself whispering. “But it’s not safe to let you out. You hurt people.”

So many people.

“I know.” The pout deepened; the head tipped forward, bringing it fully into view. “Kara wouldn’t have approved, would she.”

“No. I’m sure she doesn’t.”

The monster smiled again. Displaying, like a child, like a hunting lioness, her perfect teeth.

“Which is why I won’t let you out. It’ll be hard enough to cope with what you’ve used her hands to do once we get rid of you and bring her back, so I’m not going to let you make things worse for my—for her.”

“Oh, but we could have so much fun together,” she crooned, “just the two of us. We could go flying, Lena, and I wouldn’t drop you. I’d be very careful not to break your bones.”

A cold finger of fear clawed at Lena’s spine, from the nape of her neck, goosebumps errupting in its wake.

“We could be such good friends. Like you were with Kara. You could learn to love me just the same, and in time, you would forget she had ever been anything but me.”

The icy trace of fear turned into a burning fist, twisting in Lena’s chest, hot tongs clamped down around her heart. _“No._ You will never replace her. We’ll get her back, and we’ll get rid of you.”

Lena turned, knuckles white, nails digging into her palms, and strode away, heels booming in the silent hall.

“You can’t,” the monster said, as Lena was about to cross the threshold. “Bring her back. You can’t.”

Lena looked over her shoulder, brow arched. “Why not?”

“Because she’s dead, silly. This body, and me controlling it, is all that’s left of what she was.” The monster smiled, and this was no muscle memory. It was feral, cold. “You’ll learn, in time, to accept the way things are.”

Clutching at the concrete for stability, Lena flung herself away. Alex—Alex would know if it was true. Alex would tell her the thing was lying, Kara was safe, they could bring her back.

It would be fine.

…

“It was lying, right?” Lena asked, scraping her ponytail out of the way of her safety goggles’ strap. “Kara can’t be gone.”

Alex’s hand was pressed over her mouth. Her eyes, dark and shiny, clamped shut. Her eyelashes matted together as she inhaled sharply through her nose.

“Tell me Kara’s still in there, Alex. You have more experience with this than I do; surely, you know she’s fine, she’ll _be_ fine.” Lena adjusted the nose bridge, turned towards the miniature collider. “Right?”

The coils powered up, a dull whine.

“I don’t think I can say that, Lena.”

“Well, maybe not _fine._ Of course, coming back to all of this will feel horrible. But she’ll be back.” Lena’s thumb hovered over the switch. “Won’t she?”

Alex opened her eyes, shook her head.

Lena inhaled, picturing corrugated cardboard flaps opening, empty dark corners filling with light—Kara’s laugh, Kara’s smile, Kara’s kindness and empathy and old wounds and new fears and endless, deliberate hope.

She exhaled, closing the box, flicking the switch.

The collider chambers began to fill with light, bathing them both in the glow thrown off by the real power, the radioactive threat to Kara Danvers’ life, building.

“We have to,” Alex said dully. “This is our only option now.”

…

“It’s almost done,” Eve said, pushing her goggles up and hovering hesitantly on the other side of the table. “The Kryptonite just needs to settle for a few minutes before it’s stable enough to put into the cuff.”

Lena, clutching her paper cup of coffee that had long since gone cold, nodded mutely.

“Ms. Luthor, are you…?”

“I’m about to kill my _friend_ ,” Lena said, staring down at the murky contents of her cup, watching it ripple when her grip tightened reflexively, as if recoiling from the very concept—of Kara’s death, of causing it. “It’s a monster, I know, but it’s a monster with her face, and eyes, and of all the things my family has done, this… this will be the worst.”

After a beat, Eve sat, hands folded neatly, rigid with nervous energy. “I saw the recordings. From when they took her in. They all get saved on your computer in here, I guess because you’re the one trying to cure her. Contain her.”

She stopped herself, thankfully, before the third of Lena’s D.E.O.-assigned goals, the third IPA /k/, could be uttered.

“I just… I know this is hard for you,” Eve said. “And I don’t want to make it any harder.”

“Thank you.” Lena took a sip, swallowing what felt like a mouthful of sand. “But this will never feel like anything but impossible.”

…

Of course, Lex escaped. Like there wasn’t enough on their plates. And with Superman gone, who else could stop him but Supergirl?

Or her body. Her abilities. Her strength, her speed, her freeze breath to stop him in his tracks, her heat vision to burn the heart out of him.

Alex was going to unlock the cell, put on the cuff. She got to the bottom of the stairs and stopped as if her feet had been frozen to the floor.

“I can’t,” she whispered, clutching Lena’s arm as she continued down. “I can’t look her in the eyes and do this.”

 _Neither can I,_ Lena wanted to say, but instead, she laid her hand over Alex’s grip and said, “Do you want me to take care of this?”

Alex hesitated, chin lifting by degrees.

“It’s my mess, anyways,” Lena offered. “My Kryptonite, my Harunel, my brother.”

Alex let her chin drop, handed over the keys and the cuff.

Lena went in alone.

“See?” the monster said, with its horrible inflection shaping Kara’s voice. “I knew you would come through for me, Lena. We’re going to be such wonderful friends.”

Lena took its hand in her own, ignoring the way it tangled their fingers together, and slapped the cuff on. “If you do anything other than kill Lex Luthor, this will release enough Kryptonite into your body to completely destroy it, down to the subatomic level. Your quarks will fry like eggs if you put so much as one toe out of line.”

“Fiesty.”

Lena attempted to extricate her fingers, turning to walk away. The grip went from fond to ferocious, like she’d gotten her hands stuck in a bear trap.

“Friends hold hands, Lena,” the monster said, “don’t they?”

…

They found Lex three weeks later, a new dispersal array set up, with a new virus. He’d brought no Kryptonite; perhaps, like everyone else on the planet, he simply believed Supergirl was dead.

When he laid eyes on Kara’s body, though, the impossible shine in her eyes, the cruel twist to her smile, he smiled, took his hands off the console, pointed a gun at Lena.

“You try and stop me, Supergirl, and she dies.”

Lena laughed, shrill, unsteady. _“Really?”_

“I’ve been watching you two, you know. I know how much she cares for you, Lena. I know she’ll trade a city of lives for you if that’s the call, but will she trade a world?”

“No,” Lena said, suddenly very calm. “No, she won’t.”

The monster, eyes sizzling, was not moving. Her heat vision seemed to hesitate, microseconds from melting Lex’s face like an ice sculpture in an oven.

Then the burning light rescinded, and her eyes calmed to blue.

“Come over here, Lena,” Lex said, and she did. “Get down.”

She did that, too, knees on concrete, posture rigid but resigned. Didn’t even flinch when he pressed the gun to her temple with one hand, the other returning to the console.

“Tell me, Supergirl, what decision will you make? Tell me, Kara, are you a daughter of the House of El or not?”

Lena looked straight at the monster—blue eyes ( _somehow lost_ , Lena caught herself thinking, _somehow terrified_ ), nth metal Kryptonite cuff, eyes again—and clenched her teeth.

“Lena,” the monster said in Kara’s truest, softest voice, its unsettling inflection gone, “don’t be afraid. I’m right here. I will always be by your side, and I will always protect you.”

And Lena’s heart stopped. Just for a moment, one lurching beat of silence.

How could it know what Kara had said?

And then, in a microsecond, a nanosecond, a yoctosecond, Lena was on the other side of the bunker, and Lex was a smoking crater, and the monster was floating down at Lena’s side, offering her a hand.

“Are you okay?”

“You have her memories,” Lena said, neither moving away nor towards the proffered aid. “That’s why you said that. You know she said it to me.”

“No, Lena, it’s me!” The hand, unwilling to wait, extended further, fingertips grazing Lena’s cheek. “I meant it then, and I mean it now. I’m alive in here, and I’m going to get out before she hurts you.”

“This is a trick. You want me to take off the bracelet, you want me to—”

“‘I’m just a woman trying to make a name for herself outside of her family. Can you understand that?’”

“Oh, my god,” Lena whispered, and laced their fingers together over her face.

Kara—and it was, it had to be, in that one shining second—let her whole palm cradle the line of Lena’s jaw, brought the other hand to mirror it, knelt to her level. Lena melted, reached out unthinkingly, clutching at Kara’s cape.

“The cuff!” Lena reluctantly loosened her grip on Kara’s hand to reach for her wrist. “God, we could’ve killed you—“

“Leave it on.” Kara swallowed harshly. “We don’t have much time. She’s coming back.”

“Please don’t go.”

“I don’t have a choice. Find a way to get rid of her, okay? You’re so smart, I know you can do it. You’re the only one.”

“Kara—“

“I’m coming back. I promise. You and me, okay? This isn’t the end.” Kara pressed her lips to Lena’s forehead, and Lena’s mutilated little heart lurched pathetically against her ribs. “See you soon.”

The shining moment snuffed out, and Kara’s hands were no longer on Lena’s cheeks, or even Kara’s hands.

“What… What happened?”

Lena stood, shakily. “You killed him,” she said, hoarse. “Like you were supposed to. It was so quick. Look at the scorch mark.”

The monster looked. The starburst of ash, all that remained of the mighty Lex Luthor, still smoldered.

“Yes,” she said, “I remember now. I killed him.”

Nodding, Lena pressed her palms to her cheeks, partially to blot away any wayward tears, partially to feel the remnants of Kara’s touch, to remind herself it had happened.

Turning back and smiling once more, she said, “I liked killing him. Who’s next?”

…

“We can’t use the bracelet,” Lena said. “We can’t keep her on a leash. She has to go back.”

“Col. Hayley has orders from the President—“

“The President can take his orders and—“ Cutting herself off with a frustrated cry, Lena took off her goggles and flung them across the lab, hitting the security cameras squarely without a direct look.

The light blinked red, then went dark.

Lena reached over and grabbed Alex by the shoulders. “Kara is still alive in there.”

“No. She can’t be. Her brainwaves—“

“Forget the brainwaves, Alex, I _spoke_ to her.”

“It could’ve been playing you.”

“Lex tried to kill me, Alex, and Kara took control. Either I died or he released a biological weapon into the atmosphere, and the monster would’ve just killed him, but Kara… hesitated.”

“Hesitated.”

“Hesitated, and said things… things only Kara would know. If the monster had access to Kara’s memories, she would’ve played that trick a long time ago. Kara is still alive.”

“Then we need to get that thing out of her.”

…

The President got his way, of course, using Supergirl’s body as his own personal weapon while her mind was in purgatory. Lena stayed on as one of her handlers, watching her carefully on missions, searching desperately for any glimpse of Kara regaining control for even a minute.

“I’m not letting her out again,” the monster said one day, smoke still in the air, coming down from her flight to land on some broken body. “She caught me by surprise. I never realized how… powerful those little emotions are, but now that I know, it won’t happen again.”

“Please.” Lena swallowed thickly, fumbled for the control at her hip. “I’ll—I’ll take off the cuff. Just let me talk to her.”

Petulant, with flaming eyes, Kara’s mouth spat, “No.” She raised one hand, cupped the nth metal cuff in her palm. “You should really be nicer to me.” She _squeezed._ “Or Kara might get hurt.”

“Don’t!”

“You’re so protective of this body,” the monster said, releasing her grip, smoothing her empty palms over the lines of muscle, the angles of bone, the planes and curves of skin. “That’s nice to know. After all, you put the cuff on me; maybe you wanted it gone.”

“Don’t hurt her.”

The monster smiled. All teeth. “You first.”

…

Whenever Lena could escape the monster’s sight, she worked, frantically, to come up with a solution. A form of Kryptonite that would only work on the monster, would force it out of Kara’s body without harming Kara.

The monster proved herself so compliant that the President stopped asking for tagalong handlers, grounding Lena at HQ with only a monitor and a headset to keep her informed. She hated it; could barely look away to watch as her collider spit out different strains of Kryptonite, to observe the results of the tests she and Alex conducted on lab-grown tissues and brainwave patterns.

They could kill plants, they could shut off sunlight metabolism in cells, they could turn Kryptonian flesh into dust or Kryptonian brains into vegetables or white-hot balls of rage. They couldn’t separate the monster from its host, not in any simulation.

“What are we doing wrong?”

“I don’t know.”  
Lena turned back to her screen, watching from the monster’s perspective as she razed some government enemy to the ground. Listened to the tinny, distant reproduction of her laugh.

_See you soon._

How long until she’d broken Kara’s promise? How long until she gave up hope?

…

Eventually, word must have gotten out: the US government has a Kryptonian soldier.

Someone bought up Maxwell Lord’s old cookbook, tried to get her attention, tried to bring her down.

Too bad he was red-green color blind. The result, to him, must have seemed like perfect poison instead of ‘roid rage in a jar.

Still, the threat issued, Lena and Alex came along—someone to engineer an antidote and someone to administer it.

The monster destroyed him before they even landed, but rather than take off again, she set down far below, disappearing from view.

“After her,” Alex barked, “now!”

They landed minutes behind her, and Lena’s heart was in her throat. She raced into the compound, frantically tracking the cuff’s signal on its control console: _stun, sedate, kill_.

“Don’t worry,” Alex said, sprinting ahead, “we’ll find her.”

And then they did—in the lab, back turned.

Voice remarkably steady, Lena asked, “What are you doing?”

“Interesting,” the monster said, rattling the little glass jar and the red crystal inside. “It’s so small. I would’ve thought it was bigger. She was scared of this?”

Lena, being human, could never experience the rush of fury that accompanied a dose of Red K, but in that moment, she came close—as close as anyone could.

She crossed to the monster in long strides and snatched the tube away from her, somehow catching her by surprise.

Then the monster caught her off guard, too, and threw her across the room.

Ears ringing, Lena stayed where she landed, but still, her mouth kept running. _“That_ is dangerous. The last time someone made it, it hurt her.”

“The last time someone made it, he also made a clone. Maybe this one did, too. I’ll just take her body. This one is boring now.”

Alex, eyes fixed warily on the thing inside her sister, moved to Lena’s side and helped her sit, glanced at her eyes as if checking for a concussion.

“You kill Kara,” Lena spat, grabbing clumsily at the controls hanging from her hip, “and I _will_ kill you.”

The monster spun on her heel, groaning. “Kara, Kara, Kara! Why do you care about her so much?”

Even now, weak and bleeding and without hope, the words caught on Lena’s throat, leaving her with the utterly unsatisfying explanation she gave: “Because I do.”

The monster scoffed, and Lena stood, wobbling towards her.

“You try it, and you’re done. I’m not joking.” Lena stepped into the monster’s space, just tall enough to look her in Kara’s eyes, just close enough to feel the stellar heat that always radiated from her skin, now amped up by the thing inhabiting her. “I will abandon you, and I will die trying to burn you to the ground.”

“That’s cute,” the monster said, and then it raised its hands, one at a time, cradling her face in sickening parody of the way Kara had in their stolen, shining moment. “But I’m strong, and you’re weak.”

As if to punctuate, to prove her point, she dropped one thumb from jaw to just below, a line against Lena’s throat, and, like she had with the cuff, she _squeezed._

“Break my bones,” Lena wheezed. “Strangle me. I don’t care anymore.”

“Lena,” Alex cautioned, but Lena continued.

“You hurt her, you so much as look at another shard of Kryptonite, and I will end you. _Gladly_.”

“Fine.” The monster rolled her eyes and dropped Lena. “You don’t have to be such a baby about it.”

**Author's Note:**

> ...and then eventually lena does something brilliant and impossible and pulls kara out and then they get wifed and live happily ever after, the end
> 
> i'm so aware that this is an annoying execution of a very particular Venn diagram overlap but also like... imagine if supercorp got the same treatment... imagine if we were like "wow... _that's_ gay..." and then the show runners actually let it be gay
> 
> anyway this AU's version of "a life in a day" would be a shared black mercy hallucination in which lena and kara raise a daughter together in quiet peace and everything is fine, supercorp endgame


End file.
